This invention relates to improvements in a support apparatus for a steering column, and more particularly to the support apparatus for preventing the steering wheel side of a steering column from unexpected jumping when the steering column moves forward upon striking of a vehicle occupant at a vehicle collision.
As well known, a variety of support apparatuses for a steering column have been hitherto developed in order to prevent a so-called secondary collision of a vehicle occupant upon vehicle collision accident. One of them is disclosed in Japanese Patent Provisional Publication No. 11-115770. This support apparatus for a steering column is arranged as follows: The support apparatus includes an upper support structure and a lower support structure which are spaced from each other in the axial direction of a steering column in order to releasably fix the steering column at upper and lower two points to a vehicle body. The steering column is provided with a steering wheel which encases therein an airbag. The upper and lower support structures are in such a support condition to the steering column that each of them allows the steering column to release the steering column toward the front side of a vehicle body under an airbag inflation reaction applied to the steering column when a vehicle collision occurs. Thus, an impact absorption on the side of the steering column is cooperated with an impact absorption by the airbag. Accordingly, the above support apparatus is intended to achieve a secure impact absorption with a low cost.
In the above conventional support apparatus, when the airbag is operated or inflated, the steering column can move forward upon release of the engagement of the steering column from the vehicle body through the upper and lower support structures under the airbag inflation reaction applied to the steering column. However, in this event, the front (lower) end side of the steering column can merely move forward from the lower support structure but is restricted in releasing direction. In other words, the front end section of the steering column is not restricted in at least movement in vertical direction after it has released from the lower support structure. Accordingly, when the steering column moves forward upon receiving the airbag inflation reaction, there is the fear that the rear (upper) end section of the steering column unavoidably jumps upward under collision reaction of the vehicle occupant to the airbag. As a result, the airbag itself will jump upward through the steering wheel so that the vehicle occupant becomes out of a suitable striking position to the airbag.